The World Wide Web (WWW) is a set of tools and constructs which simplify communication between a user, using a client computer, and a server holding information which the user wishes to receive. The user's client computer and the server computer are linked together by a computer network. The user's client computer runs a computer program called a “browser”, files stored on the server are written in Hypertext Markup Language (HTML) so that the browser will interpret the file after it is transferred to the client computer, and display the file as a “Web Page”. The address of the Web Page is presented to the browser in Universal Resource Locator format or (URL), and the browser interprets this address to set up a communications session from the client to the server to transmit a request to the server, and the server reads the URL from the request in order to transmit a response to the client. The protocol used by the browser and the server application is referred to as the Hypertext Transfer Protocol (HTTP. The communications session is usually set up as a TCP/IP session, however any reliable packet transfer protocol may be used to communicate between a browser running on a client computer, and a server.
The following Requests for Comments (RFC) published by the Internet Engineering Task Force (IETF) describe various aspects of the WWW constructs: RFC 1945, “Hypertext Transfer Protocol—HTTP/1.0”; RFC 1630 “Universal Resource Identifiers in WWW”; RFC 1738 “Uniform Resource Locators (URL)”; RFC 1808 “Relative Uniform Resource Locators”; all disclosures of which are incorporated herein by reference. The Hyper Text Markup Language (HTML) is described in the book by Tim Evans, 10 Minute Guide to HTML 3.2, Second Edition, published by Que, a Division of Macmillan Computer Publishing, New York, Copyright date of 1996, all disclosures of which are incorporated herein by reference.
Network devices such as bridges (layer 2 devices), routers (layer 3 devices), layer four switches, etc. make up the computer network connecting the client computer to the server. For example, the client computer may be a desktop computer located in New York City, and the server computer may be located in California. A computer network, for example the Internet, may be used to couple the client computer with the server. A large number of network devices may be in a chain which forwards a packet from the client to the server, different packets may follow different chains of network devices, and return packets from the server to the client may follow a different chain of network devices. In any case, the client will usually be connected to a first network device, usually a router, and all packets to or from the client will pass through this first network device.
It is desirable to directly address a network device during the course of exchange of packets during a World Wide Web (WWW) communications session. For example, it would be convenient for a client to specify a class of service, for a client to specify a source of a multicast group, for a client to specify a priority for a session, etc. by communicating with a network device. However, all of the WWW protocols ignore network devices, and simply transmit packets using a routable protocol. That is, the network devices are transparent to a WWW communications session between a client computer and a server.
There is needed a simple protocol for a client computer and a server computer to communicate with a network device during a WWW communications session.